Drive for engine starters



1927' c. RINGWALD DRIVE FOR ENGINE STARTERS Filed March 20. 1925 QfwzranW Clar /nee 7% regal) aZo Patented July 5, 1927.

UNITED STATES PATENT orr cs".

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DRIVE FOB ENGINE STARTERS.

' Application filed Iarch 20, 1925. Seriallflo. 16,899.

My invention relates to drives for engine starters. Y

The present application discloses and I claims an improvement upon the device of my prior co-pending application,-Serial No. 745,555, filed October 24, 1924 Patent No.

1,597 ,330, of Aug. 24, 1926.

I am aware that heretofore it has been the practice in starting internal combustion 1C engines to employ a threaded sleeve mounted upon the motor shaft and connected to said motor shaft by a spring connection. An internall threaded drive pinion forms a nut for sa d threaded sleeve and it is moved axially into mesh with the ring gear on the fly wheel of the engine by rotation of the motor shaft and its threaded sleeve, and after the nut or pinion is meshed with said ring gear, it is rotated to turn the fly wheel and thus crank the engine.-

I In such devices, the parts must fit loosely and move easily, because the pinion nut is held by inertia while it moves axially into mesh with the ring gear. When the pinion, nut is thrown back by starting of the engine, this necessary'looseness of the parts tends to cause the pinion'nut to rebound against its stop and again engage the fly wheel gear. This is highly undesirable as it injures the gear teeth. 7 v

In devices .of this character it has been found necessary toprovide some means for holding the pinion 'against accidental rebound when the pinion is rejected by the starting of the engine. ,Here'tofore this has been accomplished by providing a supplemental detent or catch of some kind which is more or less flimsy because of the-light pressure which it must exert and the limited startlng the longitudinal travel of the memspace within which the same must be mounted. According to the present invention I V secure a novel mode of catching the pinion upon rebound, or rejection from the ring gear on the fly wheel of the engine, by causing the pinion and its threaded sleeve to put the main starter spring under longitudinal tension. In other words, I now make a double use of the main spring. The resulting holding power of the main spring working through the nut, places a certain predetermined friction upon the pinion and its connected parts, which is releasable with a certain force, which is substantially independent of the violence of rejection of the pinion .by starting of the engine. The result is a uniformity and certainty of operation not heretofore attainable in the art.

In order to acquaint those skilled in the art with the manner of constructing and operating my invention, I shall now describe a specific embodiment of the same in connection with the accompanying drawings, in which:'

Figure 1 is a side elevational view of a device embodying my invention;

Fig. 2 is a vertical longitudinal sectional view through the same;

Fig. 3 is a transverse section taken on the line 33 of Fig. 2;

Fig. 4 is a similar transverse section taken on the line 44 of Fig. 2; and

Fig. 5 is a side elevation of a modified form of pinion and sleeve.

The bearing 1 of the driving motor supports the motor shaft 2, this motor shaft having a shoulder 3 and a reduced portion 4 extending therefrom, this reduced portion being carefully ground to fit nicely the interior of the pinion and sleeve member 5 which is mounted upon said shaft 4. The pinion and sleeve member 5 is a unitary member comprising apinion 6 and a threaded sleeve 7 extending to the rear of the same. Upon the rear end of the threaded sleeve 7 I provide a stop nut or fixed collar 8'which is securely fastened upon the rear end of the threaded part 7 to provide a stop in conjunction .with the drivin nut 9 when the two parts are engaged. he pinion may engage the shoulder 3 for a stop when the device ismounted on shaft 4. A stop collar 25, as shown in Fig. 5, may be provided if f desired. In that case the stop collar 25 may provide a desired .inertia for'assisting in her 5. This stop nut 8 is preferably threaded upon the end of the threaded sleeve 7 by screw threads of fine pitch 'inclined in a direction such as to produce tightening of 'the nut 8 thereupon when it engages the collar 14. The threaded sleeve 7 has screw threads of coarse pitch, preferably of multiple thread.

The nutor threaded collar 9 is connected to the front end of a driving s ring 10, the end of the spring being forme into a loop or eye at 11 and the machine screw 12 passing radially through said eye 11 and into the nut 9 and being held against rotation by a suitable bendable lock washer 13.

At the outer end of the motor shaft 4, I

. provide a collar 14, to which the outer end and 18 are mounted under the ends of the spring 10 on the collars 14 and 9, respectively, these sheet metal sleeves serving to exelude foreign matter from the threads ofthe sleeve 7, and serving also as a support for the convolutions of the helical spring 10, and as acontainer for lubricant.

The pinion 6 and shaft 4 are mounted closely adjacent the ring gear 21 .on the fly wheel 22 of the motor, the parts being so designed as to permit the pinion 6 to run axially up to the shoulder 3 when the motor starts.

Now I wish to -call attention to the proportions or relative dimensions which are to be observed. First, the distance between the shoulder 28 and the inner radial face of the threaded collar 9 is to be substantially equal to or greater than the distance between the shoulder 3 on'the motor shaft 2 andthe ad jacent or forward end of the pinion 6, so that threaded collar 8, shown in Fig. 2, to strike.

the inner face of the collar 14 when the pinion 6 is rejected by the fly wheel when the engine is started.

I have found that it is not necessary to have the nut or collar 8 at all and I have shown, in Fig. 5, a form in whichthe collar 25 provides the required stop at the front end and the rear end of the sleeve 7 is merely smoothed off for engagement with collar 14. If the pinion 6 is stopped against shoulder 3 the collar 25 maybe omitted. I have found that generally the pinion 6 will assume a certain position, such as shown in Fig. 2, for ordinary operation where the inion 6 and connected parts are thrown ack by the ordinary force of starting of the engine and this position may coincidewith the heavy part of the nut lying below the shaft 4, shown in my prior application, or

itneed not do so. In the form shown in Fig. 5, the stop collar25 supplies a part of the desired inertia.

The operation of the device is as follows:

The shaft 4 being set closely adjacent the ring gear 21 and in proper endwise adjustment, rotation of the motor shaft 2 in the direction indicated by the arrow at the rightof Figs. 1 and 2 results in a movement of the connected parts, namely, the collar l4, bolt 16, spring 10, bolt 12, and driving nut 9. The lnertia of the pinion and sleeve member 5, together with the collar 8 or 25,'tends to hold these parts against rotation while the nut 9 is rotated to advance the pinion 6 axially, until it strikes the teeth of the ring gear 21 and meshes with the same, whereupon engagement either of the top 001- lar 8 with the end of the-driving nut 9 or pinion 6 with shoulder 3 or engagement of stop collar 25 with the ring gear 21, results in rotation of thepinion 6 and consequent driving of the ring gear 21 to crank the engine. Upon starting of the engine in the same direction at a speed greater than the speed of the pinion, the member 5 compris in the pinion 6 and the threaded-"sleeve7, wi 1 be carried back axially to the left, as in-' dicated in Figs. 1-and2. It will be obvious that, if desired, a collar 25 may be provided at the left end of the pinion 6 as shown in Figs. 1, 2, and 5, orthat if desired the pinion -6 may be run up against the shoulder 3 on the shaft 2. On the return motion the pinion stops by engaging the rear face 27 of nut 8 with the inner face of collar 14. When the rear end of the nut 8 strikes the inner face of the collar'14. the inertia ofrotation of the member 5 with its connectedparts is expended in'first, longitudinal stretching of the spring 10, that is, moving the nut 9 to. the right as viewed in Fig. 2, and also in the friction of motion between the rounded face 27 of the nut 8 and the inner face of the collar 14, and also the friction of mot-ion between the threaded part 7 and the nut 9. I prefer to round the nutor collar Sat its rear end so as to minimize the friction between said rounded end 27 and the collar 14. The nut 8 may in fact be dispensed with and sleeve 7 directly engage col ar 14. Since the spring 10 is stretched lengthwise, by movement of the collar 9 to the right when the pinion is rejected by the starting of the engine, the resultant holding power will be substantially uniform for widely varying degrees of force of rejection of the pinion 6 and positions of the connected parts. This is because the endwise tension under which the spring 10 is placed acts upon the inclined surface, namely, the helical threads, and the angle of these threads is such that the tangent of the angle is less than the co-eificient of friction between the nut and the thread. This means that under any degree of tension. within limits the spring 10 will not be able to rotate the threaded sleeve 7 by pulling endwise on the nut 9, but also at the same time it means that all that is required is to overcome the initial friction between these parts and thetension of the spring tends to assist the rotation between the parts. Hence, no matter how vio- .lently the rejection of the pinion 6 and connected parts. by the starting of the engine, there is no tendency for the pinion to rebound into the teeth of the ring gear 21, as has been the case in structures of the prior art. 1

From the foregoing, it will be seen that I have provided a construction which permits of the use of a pinion of a minimum number of teeth and of a minimum diameter with a maximum starting torque. At the same time, the rearwardly extending threaded sleeve 7 gives the pinion 6 the desired inertia without increasing the diameter of the same, and this makes for simplicity with certainty of operation. The pinion 6 is held accurately and with much greater bearing on the round shaft section 4 that has been possible in devices of the prior art. The interior of the sleeve may be relieved as indicated at to minimize friction. It will be noted that the pinion can be brought up to the motor bearings, since no collar is required at the inner end of the pinion as in devices of the prior art, and better support is thereby gained. The double function of spring 10 effectually holds the member 5 with just the desired amount of holding power independ- 1 ently of'the violence of back throw of the pinion. In addition to the above advantages, the construction is less expensive and involves a less number of parts.

I claim:

1. In combination, a tubular member having a pinion at one end, a threaded sleeve at the other, a threaded collar on said threaded sleeve, an attaching collar, and a helical drive spring connected to and lying between said two collars, said sleeve being long enough to engageend-Wise the inside face of the attaching collar when the sleeve is threaded back through the threaded collar as by starting of the engine.

2. In combination, a driving shaft, a onepiece sleeve and pinion member mounted on said driving shaft, a threaded nut on said sleeve, an attaching collar mounted on and secured to the driving shaft, and a connecting spring between the collar and the nut, and telescoping with the sleeve, the rear end of the sleeve engaging the attaching collar.

3. In combination, a shaft having a collar, a threaded sleeve on said shaft, the end of the sleeve being adapted to engage the collar,

a. pinion on the other end of the sleeve, a collar threaded on the sleeve and lying adjacent said pinion, and a driving spring connected between the first collar and the threaded collar and telescoping with the sleeve.

4. In combination, a threaded sleeve having a stop collar at one end and a pinion at the other, a driving collar engageable by the stop collar-when the pinion is thrown back, a threaded collar vco-operating with the threaded sleeve, and a helical spring connected betweenthe driving collar and the threadedcollar, said spring being stretched upon engagement of the stop collar with the driving collar.

5. In combination, a sleeve member having a pinion-on one end, a thread upon the other, fthreaded collar on said threaded part of the sleeve member, an attaching collar, a drive spring between said two collars and a. stop on the threaded end of the sleeve for engaging the threaded collar to stop the forward movement of the member, said stop being adapted to engage endwise the inner side of said first collar to stop the backward movement of'the member.

6. In combination, one-piece sleeve and pinion member mounted on a driving shaft, a threaded nut on said sleeve, said sleeve having a threaded portion with a shoulder at the rear end of the threaded portion, an attaching collar mounted on and secured to the motor shaft, and a connecting spring between the collar and the nut, and telescoping with the sleeve, the shoulder at the rear end of the threaded portion engaging the attaching collar.

7. In combination, a motor shaft having a sleeve member closely fitting thereupon, said sleeve having a pinion rigid with one end thereof, threads formed on "the sleeve, a collar embracing said sleeve and having internal threads cooperating with the threads on the sleeve, a coil spring having one end attached to said collar and the other end attached ,to the shaft for transmitting the torque of the motor through the spring to the collar, there being means engaged by the sleeve when said sleeve is threaded into the collar, placing said spring under endwise tension, the pull of the spring acting through said'threaded parts being not great enough to turn the sleeve, but tending to reduce the effect of the friction between the sleeve and the parts that contact therewith to provide ease in starting to thread the sleeve out of the collar. p

In witness whereof, I hereunto subscribe my name this 16 day of March, 1925.

CLARENCE BINGWALD. 

